BMW Invention Boosts Efficiency of Composite Molding

BMW is developing a roll-fed technology to produce thermoplastic composite parts that reduces costs and improves efficiencies.

In the new system, a roll of glass or carbon fiber mat is fed first into a heating unit where it is consolidated and then into a mold where it is cut off and then overmolded.

A recent patent application states: “The energy balance is improved since heating for consolidating, forming and the injection-molding process is necessary only once. The complicated handling devices in the case of a large number of, or large, organo sheets and the necessary higher manufacturing tolerances for consolidated organo sheet inlay parts can be eliminated.”

In Europe, thermoplastic composites are often called “organo” sheets.

European auto producers—more so than in the United States—are aggressively introducing thermoplastic composites to replace metal both for weight savings and the beneficial properties of the composites.

The patent application states: “In fabrics and crosslays, the fibers can also extend at right angles to one another, such that the mechanical properties of organo sheets, such as rigidity, strength and thermal expansion, can be defined better than in their metal precursors. In contrast to metal sheets, the tensile and compressive behavior and other mechanical and thermal properties are not isotropic.”

The thermoplastic composites also are also more corrosion resistant than steel.

New equipment required to implement the technology include: 

  • A receptacle for a roll on which a not yet consolidated endless organo sheet is wound;
  • A heating unit;
  • A gripper for drawing a front portion of an endless organo sheet from the roll and for introducing the front portion into the heating unit; and
  • A cutting unit which is arranged between the heating unit and the injection mold.

In the BMW invention, a roll of carbon or other type of fiber sheet (2) is pulled from a roll (3) into a heating station (5) and then pulled by a gripper and clamp (6) into an open injection mold, where it is overmolded with thermoplastic into a part (1). The invention eliminates complicated handling equipment and reduces energy use. (USPTO)

About Doug Smock

Former Chief Editor at Plastics World and Senior Technical Editor Design News
Automation/Robotics, Automotive, Carbon Composites, Europe, Insert Molding, Reinforcing Material , ,

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